Auxiliary fuel vaporizer system for an internal combustion engine

ABSTRACT

A fuel vaporizer apparatus and method for an internal combustion engine has a hydrocarbon separator incorporated into the engine fuel supply system. Fuel is heated and injected into a vessel chamber, admixing therein with air under controlled volume flow rates resulting in the passage of a vaporous lighter end hydrocarbon and air admixture to the carburetor for a preselected period. Thereafter contacting means synchronously terminates the introduction of said admixture, and initiates the passage of a liquid fuel into the carburetor.

United States Patent [191 Alquist et al. I

[111 3,845,749 [451 Nov. 5, 1974 AUXILIARY FUEL VAPORIZER SYSTEM FOR AN INTERNAL COMBUSTION ENGINE Inventors: Henry E. Alquist; Lyle W. Pollock;

Glenn H. Dale, all of Bartlesville, Okla.

Phillips Petroleum Company, Bartlesville, Okla.

Filed: July 30, 1972 Appl. No.: 268,788

Assignee:

U.S. CL. 123/133, 60/285, 123/122 H Int. Cl. F02m 17/18 Field of Search 123/179 G, 180 E, 180 P, 123/180 T, 180 R,133, 122 15,122 F,122 H, 121, 127, 3, 35

References Cited UNITED STATES PATENTS Crain 123/133 Dienner 123/3 UX EXHAUST TEMPERATURE RES PONSIVE 2,192,067 2/1940 Betry 123/127 2,219,522 10/1940 Hinsch 123/133 UX 2,315,882 4/1943 Trimble et al. 123/121 3,448,733 6/1969 Aske 123/180 R 3,718,000 2/1973 Walker 123/121 X Primary Examiner-Charles J. Myhre Assistant ExaminerR. H. Lazarus [57] ABSTRACT 8 Claims, 1 Drawing Figure FUEL =- FLOAT VALVE TO Fuel. TANK AUXILIARY FUEL VAPORIZER SYSTEM FOR AN INTERNAL COMBUSTION ENGINE This invention relates to a method and apparatus for providing a controlled start-up fuel vapor-air blend. In

another aspect this invention relates to a method and apparatus for lowering engine start-up emissions. In yet another aspect this invention relates to an alternative to the internal combustion engine choke.

The causes of poor starting under cold conditions are related and interdependent; thus elimination of any one cause will often result in elimination of the problem of poor starting. The present invention is designed to eliminate the chief cause of poor starting, which is poor fuel vaporization, by providing an auxiliary source of heated fuel vapor-air admixture to be used in starting the engine. If a sufficient amount of dry fuel vapor-air admixture is available to the engine immediately upon the initiation of starting operations, the engine will start even though the cranking speed is slow and the spark weak.

ln gasoline engines, poor fuel vaporization results from the low volatility of gasoline at low temperatures. Since gasoline is not a pure substance, but a mixture of hydrocarbons of varying molecular weights and properties, vaporization takes place over a wide temperature range with complete vaporization occurring at approximately 400F. At an ambient temperature of F., for example, only about percent of the gasoline flow into the carburetor is converted into a vapor. Even this small amount of vapor will frequently not reach the cylinders since much of it rapidly condenses when it comes in contact with the cold engine. Under these conditions, over 90 percent of the gasoline passing through the carburetor remains in liquid form and does not mix with the incoming air to form a combustible fuel vapor-air mixture. lf combustion of the limited amount of gasoline vapor does not occur within a few turns of the engine, the engine will flood and become impossible to start until the flooding condition is cleared.

New challenges for cold engine starting have arisen from the emission standards now being imposed, for example, on the 1975 automobile. The 1975 automobile exhaust emission standards, based upon a 23-minute driving cycle from a cold start, are proving to be most difficult to meet because of the high emissions which occur within the first few minutes of engine operation. Approximately 46 percent of the total hydrocarbon and carbon monoxide emissions in a 7.5 mile simulated trip are released in the first 2 minutes, during which time an exhaust catalytic converter is warming up and ineffective. These high emissions during early engine operation are primarily due to engine choking which is vital to satisfactory automobile performance during start and warm-up. The start-up situation presents a problem wherein a desirable fuel would be a liquid that approaches the warm-up performance and emission characteristics of propane, but is not so volatile as to cause fuel handling and evaporative problems.

Choking during cold start-ups for the internal combustion engine is required for adequate performance and has been an established procedure for many years. Regardless of ambient or engine operating temperatures, an automobile engine delivers, for example, maximum power at a vapor-air mixture of l 10 percent stoichiometric fuel. With a cold intake manifold, the ordinary carburetor must meter a liquid. fuel-to-air mixture much richer in order to achieve this 1 10 percent stoichiometric fuel best power" vapor-air mixture. The choke achieves this best power mixture by throttling the air supply and by reducing the pressure in the vicinity of the fuel nozzles to help vaporize the liquid fuel. A suitable alternative for the automobile choke is to provide a vapor-fuel supply during a start and warm-up period.

The basic incompatibility of the modern choke system with the 1975 exhaust emission standards and the high costs involved in making a more volatile fuel demand that alternative approaches to the start-up problem be explored. Furthermore, summer motor fuel volatility must be considered as well as cold climate fuel requirements. One approach to minimizing the choke is to start and warm up the engine on the hydrocarbons containing mainly butanes (C and pentanes (C which are in present gasolines and then, at the time when the choke normally ceases its operation, to operate the engine from the normal carburetor with a slightly debutanized and depentanized fuel. Although this approach represents a departure from present fuel system designs, it has the advantage of requiring only one liquid fuel supply and may reduce the need for a gasoline of 250F., maximum percent distillation temperature. This means that 90 percent of the fuel is evaporated at 250F. ASTM specification D439 for current gasoline specifies a maximum temperature of 365F. for 90 percent of fuel evaporated. This alternative to the choke would require a device for stripping light hydrocarbons from the gasoline under controlled admixing conditions for preselected periods.

The present invention provides a method and apparatus which is an alternative to the internal combustion engine choke. Our invention comprises a small debutanizer vessel incorporated into the fuel supply system wherein the vessel receives an internal spray of fuel through a heated nozzle during engine start and warmup periods. An air stream flowing through the vessel carries lighter constituents, butanes and pentanes, for example, to the carburetor. Debutanized fuel accumulates in the vessel and flows to the carburetor at the end of a preselected warm-up period.

It is an object of this invention to provide an alternative to the internal combustion engine choke. It is another object of this invention to lower start-up and warm-up emissions. lt is yet another object of this invention to provide a method and apparatus for improving start-up fuel vapor-air blends.

The principal features of the method and apparatus according to the invention required to accomplish the objectives set out hereinabove provide a start-up and early warm-up fuel vapor-air mixture for a standard car (12 miles per gallon) which requires three chokeassisted starts per day and operates for about 21 miles per day. During urban operation, such a vehicle would use air at an average rate of 0.0406 lbs/sec., but said rate can vary between 0.013 and 0.095 lbs/sec. during the warm-up period.

The method and apparatus according to the invention is presented herein using a realistic gasoline composition representative of gasolines now on the market. An example gasoline was chosen which was defined by the American Petroleum Institute as being representative, in terms of both physical properties and composition, of the average summer gasoline marketed in the United States. Inspection data on this fuel is shown in Table 1.

TABLE I PHYSICAL PROPERTIES AND COMPOSITION OF U.S. AVERAGE SUMMER GASOLINE Distillation. F*

Initial boiling point l pct evaporated 126 20 pct evaporated M4 30 pct evaporated l64 40 pct evaporated I85 50 pct evaporated 2l() 6() pct evaporated 231 70 pct evaporated 252 "Reid Vapor Pressure. 1b.. ASTM D 32] The principal features of the method and apparatus according to our invention required to accomplish the start-up and warm-up objectives as stated hereinabove are shown schematically in the drawing. Referring in detail to the drawing, there is shown an auxiliary fuel vaporizer system 1 for an internal combustion engine (not shown). The fuel vaporizer system 1 has a vessel 2 having a chamber 3. The vessel has an upper end 4 and a lower end 5. The vessel lower end 5 has an opening 6. The chamber 3 has a lower portion 7 and a float control means 8 located therein. The float control means 8 is connected to a solenoid drain valve 9 which is in communication with the vessel lower end opening 6.

The vessels upper end 4 has a first opening 10, a second opening 11, and a third opening 12. The vessel upper end first opening 10 communicates with an air intake means 13 which is connected through conduit means 14 to an air filter. not shown. The air intake means 13 has a venturi inlet 15 in communication with valve 16 on fuel conduit 17. The valve 16 in communication with the venturi inlet 15 provides a control means for the fuel flowing to the vessel 2 through conduit 18.

Fuel is provided from a fuel tank and pump, not shown. through fuel conduit l8, 19 to a heated spray nozzle 20 in communication with the vessel upper end second opening 11. The heated spray nozzle 20 has a spring loaded nozzle 21 which is inserted into the chamber 3. The fuel inlet spray means 22 is controlled by the venturi inlet 15 which controls valve 16 located on fuel conduit 17 thereby providing a controlled fuel flow through conduit 18 and nozzle 21 in proportion to air flow through conduit 14.

An air-fuel vapor outlet 23 communicates with the vessel upper end third opening 12 and an air-fuel vapor conduit 24. The air-fuel vapor conduit 24 communicates with a carburetor 25 through the primary carburetor section 26. Additional air is provided to the carburetor through carburetor air intake 27 and is controlled by the carburetor throttle rod 28 and butterfly valves 29. The carburetor communicates with the intake manifold 30 of an internal combustion engine, not shown. An exhaust gas thermostat 31 communicates with an electro-mechanical relay system 33 providing control means for the auxiliary fuel vaporizer system 1.

The carburetor bowl 36 communicates through fluid conduit 37 with solenoid drain valve 9. Fluid conduit 38 provides a fuel return through fuel conduit restricor 39 to the fuel supply tank, not shown.

in the method of this invention, prior to the time that the internal combustion engine is to be started, an operator places the automobile engine ignition system switch 32 in the on position, thereby starting the electric fuel pump in the supply tank and closing the solenoid drain valve at the bottom of the vaporizing vessel chamber 3. By virtue of the valve arrangement as shown, cranking the engine causes air to be pumped through the debutanizer vessel 2 via the venturi inlet 15 to the debutanizer chamber 3. Needle valve 16, which is normally open, is partially closed by the vacuum generated by air flow through the venturi 15 into the debutanizer. The aforementioned combination of events forces a fuel spray into the debutanizer through the spring-loaded nozzle 21. Regardless of the quantity of air flowing through the debutanizer, about 3 mols of fuel are admitted for each 2.5 mols of air by virtue of control valve 16. Fuel in excess of the quantity required by-passes the debutanizer vessel back to the tank by way of conduit 40. When the ignition switch is turned on and the exhaust gas thermostat 31 is in a cold position, the electrical heating element 20 is activated through the action of the electro-mechanical relay 33 to compensate for the temperature drop at the nozzle caused by the vaporizing fuel. Heating element 20 releases approximately 25 BTU/min, requiring approximately 440 watts.

An exemplary operation of the apparatus according to the method of the invention would provide a total of about 830 grams of gasoline to be sprayed into the debutanizer through the nozzle during approximately seconds of operation. About 103 g. (15.7 weight percent) of this sprayed liquid is vaporized and swept overhead by the air flow. The overhead vapor-air mixture consists of about 18.7 mol percent hydrocarbon and about 8L3 mol percent air with about 73.5 mol percent of the hydrocarbon being butanes and pentanes.

Initially there is no liquid gasoline in the debutanizer and the float rests at the bottom of the chamber. Tank fuel is available to the carburetor bowl until the debutanized gasoline raises the float to its top position in the lower portion of the chamber which, in turn, rotates valve 9 so that only debutanized gasoline can flow to the carburetor bowl. The normal carburetor bowl needle valve permits liquid flow in accordance with the engine needs. After about 420 g. of debutanized gasoline have accumulated in the debutanizer chamber, and about 60 seconds have elapsed, the butterfly valve 42 begins to open in the normal carburetor air horn and the butterfly valve 42A in the fuel vapor-air supply horn 26 begins to close. These valves are thermostatically and simultaneously controlled by exhaust bas thermostat 31 in the same fashion as present automatic chokes, but are located below throttle plates 29 and 29A. The effect of this pair of valves is to cause the engine to operate progressively on a decreasing portion of the debutanized overhead product and an increasing portion of debutanized gasoline from vessel 2 by way of bowl 36. This transfer mode" requires a period of about 40 seconds. Thermostat 31 which initiates the transfer mode also turns off the heater on the fuel injector nozzle.

Upon completion of the transfer mode, air no longer flows through the debutanizer, the fuel spray is stopped, and the fuel supplied by the pump by-passes the debutanizer and returns to the tank by conduit 40. The carburetor relies completely for its fuel supply on the debutanized gasoline until the float 8 drops to the bottom ofthe debutanizer. The dropping of the float to the bottom of the debutanizer switches the position of valve 9 so that the carburetor receives tank fuel.

At the completion of use of the engine, the ignition is turned off. The exhaust cools and the butterfly valves 42 and 42A in the carburetor air horns begin to return to their cold positions. The fuel heater relay is set to turn the heater on when the ignition is turned to an on position through the electro-mechanical relay means. Should a start be attempted before the engine is completely cold, the engine will start in some stage of the transfer mode with a portion of the fuel being supplied as vapor from the debutanizer. Valve 9 remains in a position where tank fuel is supplied to the carburetor bowl until the debutanizer float lifts to its top position, thus activating valve 9 and providing further operational results as discussed hereinabove.

Other modifications and alterations of this invention will become apparent to those skilled in the art from the foregoing discussion and accompanying drawing,

and it should be understood that this invention is not to be unduly limited thereto.

What is claimed is: 1. Apparatus to supply fuel-air mixtures to an internal combustion engine comprising:

a carburetor having first and second sections, each adapted to convey fuel and air to the engine; a first valve in said first section and a second valve in said second section; first fuel supply means connected to said first section to deliver liquid fuel thereto from a fuel tank; an evaporation vessel having a first outlet in the upper region thereof and a second outlet in the lower region thereof; second fuel supply means connected to said vessel to deliver liquid fuel thereto from the fuel tank; inlet means in said vessel to permit introduction ofair into said vessel; conduit means extending between said first outlet and the second section of said carburetor to convey vaporized fuel and air from said vessel to said second section;

a temperature sensing means adapted to sense the temperature of exhaust gases from the engine; and

.means responsive to said temperature sensing means to control said valves to open said first valve and close said second valve when the measured temper ature reaches a predetermined value.

2. The apparatus of claim I, further comprising a float positioned to detect a liquid level in said vessel, and means responsive to said float to pass liquid fuel from said vessel to said first chamber when the liquid level in said vessel reaches a preselected height.

3. The apparatus of claim ll wherein said inlet means comprises a conduit having a venturi therein, said first fuel supply means comprises second conduit means adapted to extend from the fuel tank to said first section, a valve in said first conduit means, said second fuel supply means comprises third conduit means extending between an upper region of said vessel and said second conduit means upstream of said valve, and further comprising means to move said valve toward a closed position in response to flow of air through said venturi.

4. The apparatus of claim 3, further comprising a heater connected to said second fuel supply means to elevate the temperature of the fuel to facilitate vaporization thereof in said vessel.

5. The apparatus of claim 2 wherein said first fuel supply means includes a fuel bowl which receives fuel and from which the fuel is delivered to said first section of said carburetor.

6. An auxiliary fuel vapor system for an internal combustion engine, comprising:

a vessel having a chamber and upper and lower ends, said upper end having a first, second, and third opening into the chamber and said lower end having an opening into the chamber;

an air intake element in communication with the chamber through the upper end first opening of the vessel;

a fuel intake element in communication with the chamber through the upper end second opening of the vessel;

a spray nozzle on the discharge end of the fuel intake element within the vessel;

first means for heating and passing fuel through the fuel intake element, the spray nozzle, and into the vessel;

second means for passing air through the air intake element and into the vessel;

a carburetor having first and second sections;

a fuel bowl in communication with said first section;

third means for passing vapors from the vessel chamber, through the upper end third opening of the vessel, and into the second section of the carburetor; fourth means for passing fuel into the bowl; means for controlling the passage of fuel into the vessel in response to the flow of air into said vessel;

means to sense the temperature of exhaust gases from the engine and to terminate the flow of vapors to said second section and initiate the flow of fuel from the bowl into said first section when the sensed temperature reaches a predetermined value;

a float within the vessel; and

means responsive to the float rising to a predetermined level to pass collected liquid fuel from said vessel to said first section.

7. A method of supplying fuel to an internal combustion engine from a single source of liquid fuel comprising:

initially spraying liquid fuel from the source into a stream of air to partially vaporize the fuel; passing the stream of air containing the vaporized fuel into the engine;

spraying step; and I passing fuel to the engine from said source after the collected fuel has been used. 8. The method of claim 7 wherein the fuel sprayed into the air stream is heated to facilitate vaporization of the lower boiling constituents thereof.

v UNITED STATES PATENT OFFICE v CERTIFICATE OF CORRECTION Patent NO. 9 Dated November 5, 1974 Hen E. A Inventofls) 'ry lqulst et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line I22]; delete 'Fziled; July 30, 1-972 and insert therefor Filed: July 3, 1972 H.

Signed and sealed this 4th day of February 1975.

(SEAL) Attest:

McCOY M. Attesting Officer USCOMM-DC 603764 69 u.s. sovnmntm PRINTING OFFICE: 93 0 FORM PO-10SO (.0'69) 

1. Apparatus to supply fuel-air mixtures to an internal combustion engine comprising: a carburetor having first and second sections, each adapted to convey fuel and air to the engine; a first valve in said first section and a second valve in said second section; first fuel supply means connected to said first section to deliver liquid fuel thereto from a fuel tank; an evaporation vessel having a first outlet in the upper region thereof and a second outlet in the lower region thereof; second fuel supply means connected to said vessel to deliver liquid fuel thereto from the fuel tank; inlet means in said vessel to permit introduction of air into said vessel; conduit means extending between said first outlet and the second section of said carburetor to convey vaporized fuel and air from said vessel to said second section; a temperature sensing means adapted to sense the temperature of exhaust gases from the engine; and means responsive to said temperature sensing means to control said valves to open said first valve and close said second valve when the measured temperature reaches a predetermined value.
 2. The apparatus of claim 1, further comprising a float positioned to detect a liquid level in said vessel, and means responsive to said float to pass liquid fuel from said vessel to said first chamber when the liquid level in said vessel reaches a preselected height.
 3. The apparatus of claim 1 wherein said inlet means comprises a conduit having a venturi therein, said first fuel supply means comprises second conduit means adapted to extend from the fuel tank to said first section, a valve in said first conduit means, said second fuel supply means comprises third conduit means extending between an upper region of said vessel and said second conduit means upstream of said valve, and further comprising means to move said valve toward a closed position in response to flow of air through said venturi.
 4. The apparatus of claim 3, further comprising a heater connected to said second fuel supply means to elevate the temperature of the fuel to facilitate vaporization thereof in said vessel.
 5. The apparatus of claim 2 wherein said first fuel supply means includes a fuel bowl which receives fuel and from which the fuel is delivered to said first section of said carburetor.
 6. An auxiliary fuel vapor system for an internal combustion engine, comprising: a vessel having a chamber and upper and lower ends, said upper end having a first, second, and third opening into the chamber and said lower end having an opening into the chamber; an air intake element in communication with the chamber through the upper end first opening of the vessel; a fuel intake element in communication with the chamber through the upper end second opening of the vessel; a spray nozzle on the discharge end of the fuel intake element within the vessel; first means for heating and passing fuel through the fuel intake element, the spray nozzle, and into the vessel; second means for passing air through the air intake element and into the vessel; a carburetor having first and second sections; a fuel bowl in communication with said first section; third means for passing vapors from the vessel chamber, through the upper end third opening of the vessel, and into the second section of the carburetor; fOurth means for passing fuel into the bowl; means for controlling the passage of fuel into the vessel in response to the flow of air into said vessel; means to sense the temperature of exhaust gases from the engine and to terminate the flow of vapors to said second section and initiate the flow of fuel from the bowl into said first section when the sensed temperature reaches a predetermined value; a float within the vessel; and means responsive to the float rising to a predetermined level to pass collected liquid fuel from said vessel to said first section.
 7. A method of supplying fuel to an internal combustion engine from a single source of liquid fuel comprising: initially spraying liquid fuel from the source into a stream of air to partially vaporize the fuel; passing the stream of air containing the vaporized fuel into the engine; collecting the remainder of the liquid fuel which is not vaporized from the spraying step; sensing the temperature of the exhaust gases from the engine; terminating the spraying step when the sensed temperature reaches a preselected value; thereafter passing the collected fuel to the engine in place of the vaporized fuel resulting from the spraying step; and passing fuel to the engine from said source after the collected fuel has been used.
 8. The method of claim 7 wherein the fuel sprayed into the air stream is heated to facilitate vaporization of the lower boiling constituents thereof. 